Whereas others may find the decommissioning issue daunting in its complexity, Sinn Fein's chief negotiator, Martin McGuinness, believes it is all very simple.

The world holds its breath for Gen de Chastelain's long-awaited report on decommissioning next Tuesday. Mr McGuinness has been in regular contact with the general since last September, so what does he expect the report to contain?

"I don't know what he will say," he confesses. "From our perspective, we have been unhappy that the decommissioning body has not effectively stamped its authority on the issue in the course of the last year. People could be forgiven at times for thinking that David Trimble and the Ulster Unionists were in charge of the issue of decommissioning rather than Gen. de Chastelain."

In his view the decommissioning body should from the very beginning have "laid the law down" to everyone that, "as Patten was going to be in charge of the Patten Commission on policing, they were going to take charge of their own affairs and not be dictated to by anyone and to make it quite clear that they were going to rigidly stick by the terms of the Good Friday agreement".

What Sinn Fein believes the general and his colleagues on the decommissioning body need to do is "effectively what Tony Blair asked everybody to do last week in his Belfast speech, to get back to the Good Friday agreement.

While acknowledging that the public is confused as to the requirements set out in the decommissioning section of the Good Friday document, to Martin McGuinness the clauses are perfectly clear.

"The challenge was to, first of all, set up the institutions, to inject dynamic into the process, to bring about the implementation of all aspects of the agreement dealing with equality, injustice, human rights, policing, prisoners and to effectively make that the engine of the process so that, once you effectively remove the reasons why people feel the need to rise up in arms, then the issue of how you remove all the guns from Irish politics becomes very straightforward."

He claims there are "people out there who should know better, who are trying to muddy the waters" over decommissioning. That the Ulster Unionist Party was "riven with divisions and splits" was also creating a difficulty. As a politician from another party had said to him: "The problem with the unionists is that they want the trappings of power at Stormont but they have no real belief in the Good Friday agreement."

Earlier this week Mr McGuinness called for the Assembly to be closed and members' salaries suspended if an executive were not established by Wednesday's deadline. Would Sinn Fein walk away from Stormont if the deadline was passed but the Assembly remained in existence, as David Trimble and other unionists have suggested it should?

"All of these matters in relation to Sinn Fein's response to a failure to set up the institutions which were agreed over a year ago will be discussed by the Sinn Fein ard chomhairle executive council and they will decide our attitude to all of that.

"Now, that said, I think clearly if by next Wednesday the institutions are not up and the agreement has not been implemented then the Assembly loses credibility. For many people on the ground there will be a view that the unionists are attempting to `pocket' the Assembly and effectively veto everything else which envisages fundamental change, within the Good Friday agreement.

"The agreement makes it absolutely clear that the Assembly and the executive and the all-Ireland ministerial council are interdependent, that you can't have one without the other."

There is one question that seems to cause the Mid-Ulster MP some momentary hesitation. Did he think the British and Irish governments knew what they were doing?

"I would like to think that the two governments know what they are doing," he replied. "And I have to say that the Taoiseach and Tony Blair are very well disposed towards bringing the type of change that we all know needs to happen in the North."

HE is less benign in his assessment of the Ulster Unionists. Recalling Jeffrey Donaldson's walk-out on Good Friday over decommissioning, he said: "A battle has been fought every day since then. The rejectionist unionists, led from within David Trimble's party by Jeffrey Donaldson and others, have in my opinion effectively politically paralysed Mr Trimble in relation to the implementation of the Agreement."

If Mr Donaldson now rejoined the UUP negotiating team, as had been suggested, it would "not augur well for a resolution of this impasse".

Mr McGuinness points out that he is the only representative appointed by any of the larger parties to liaise with the decommissioning body despite the fact that this was not required under the agreement.

"It is absolutely vital that people understand that the key phrases in the decommissioning section of the agreement are that the responsibility to try and bring about decommissioning within the time-frame rests with all of the participants. It's a collective effort. People could be forgiven for thinking that this is an issue that only Sinn Fein must deal with: totally and absolutely wrong. The agreement is very, very clear.

"It also says that we have to try and use our influence in the context of the implementation of the Good Friday agreement. I have told Gen. de Chastelain that it's impossible to even deal with this issue because we are working in the context of the non-implementation of the Good Friday agreement and that it is absolutely essential that David Trimble be told that this is an impossibility."

The First Minister should be told that his job was "to work in a collaborative fashion with the rest of us to try and create the conditions on the ground which will make it possible for those in possession of arms to voluntarily - and we all agreed from the very beginning that George Mitchell was wise when he said that this had to be a voluntary exercise - disarm and remove the gun from Irish politics".

That task would have been a very difficult one at the best of times, but not impossible in his opinion. But it had been "made impossible" by the fact that the Ulster Unionists seized on the issue and tried to "use it as a weapon to beat Sinn Fein over the head".

So was it a realistic possibility, in his opinion, to achieve total decommissioning by May 2000, as envisaged under the agreement? "We have lost a year. With the delaying and the stalling and the messing about that has gone on, a vital year has been lost."

There were now less than 12 months left before that deadline. "That said, if we can get the executive up before next Wednesday and operate and implement the Good Friday agreement as agreed, all of the participants including Sinn Fein have to put their shoulder to the wheel in relation to the fullest implementation of the Good Friday agreement, every section of it."

Removing the causes of conflict was more important than decommissioning. "Once you clearly have everybody on the same wavelength, that is, that the process is unstoppable, that change is coming and that there are politicians from every area of politics, i.e. unionism, loyalism, nationalism and republicanism, working together, speaking with one voice, then the issue of how you remove guns becomes very straight forward."

SO had he formally asked the IRA to decommission? "From our point of view in Sinn Fein, we - and maybe people think this is a fault - only like to ask the question when we have a fair idea of what the answer is going to be. The danger is that asking the question and getting a negative could actually be detrimental to the type of work which we are involved in."

I put it to him that, while the two prime ministers now appeared to accept that decommissioning was not a precondition for Sinn Fein membership of an executive, there had been a proposal in the air for some time - put forward originally by Mr Seamus Mallon - whereby the republicans would be removed from office after, say, six months, if decommissioning had not taken place.

"There is no linkage between decommissioning and the right of any party to sit on an executive. What parties must do, who are entitled to ministries on an executive, is take a pledge of office and show their commitment to peaceful and democratic methods. Sinn Fein is quite prepared to do that. The only test that we had to pass to gain membership of the executive was the election to the Assembly last year. We had 18 people elected: that entitled us to two ministerial positions."

Any attempt to make Sinn Fein office-holders subject to a decommissioning timetable would be "a serious blunder and mistake". Making the retention of their portfolios contingent on weapons disposal would be to change the spirit and the letter of the agreement.

With the prospects for a successful conclusion to next week's negotiations looking distinctly uncertain, I nevertheless asked Mr McGuinness, Sinn Fein minister-designate, which pair out of the 10 ministries on offer his party would be seeking on his behalf. He points out that the ministries are allocated under the d'Hondt system of proportionality which limits the choices available to the smaller parties in particular.

"We will still get a big department, and hopefully two big departments."